[cfe-dev] Silencing an analyzer warning

[Ted Kremenek]

Yes, an annotation would make more sense in this case.  This particular checker employs has the cf_retains_retained and ns_returns_retained attributes to make it smarter about return values.

This case is a little trickier, however, as it isn't a blanket property of curl_easy_setopt, but in how it is used in this particular instance.

On Apr 29, 2010, at 10:02 AM, Jeffrey Yasskin wrote:

> Wouldn't it make more sense to add annotations to the analyzer so that
> users can annotate that curl_easy_setopt steals a reference from its
> third argument or that the caller promises to release that argument at
> the same time as they release 'handle'? Then the analyzer would have
> enough information to complain when a caller _forgot_ to CFRetain that
> argument, instead of just hiding both kinds of mistakes.
> 
> Obviously an escape hatch is useful too, for cases that don't have
> analyzer support yet, but it shouldn't be the long-term fix.
> 
> Jeffrey
> 
> On Thu, Apr 29, 2010 at 9:21 AM, Ted Kremenek <kremenek at apple.com> wrote:
>> There is currently no good way to silence warnings using attributes or pragmas, but you should be able to get around the issue with a wrapper function:
>> 
>>  static inline CFTypeRef CFRetainForCurl(CFTypeRef obj) { CFRetain(obj);  return obj; }
>>  ...
>>  curl_easy_setopt(handle, CURLOPT_PRIVATE, CFRetainForCurl(result));
>> 
>> This isn't a permanent solution; it's essentially relying on a deficiency in the analyzer when it comes to wrapper functions (and so eventually a leak will be reported for this case as well).  However, the plan is to eventually add pragma support (or something like that) to silence specific analyzer warnings.
>> 
>> On Apr 29, 2010, at 5:08 AM, Joe Ranieri wrote:
>> 
>>> CURL *handle = curl_easy_init();
>>> RequestInfo *result = [[[RequestInfo alloc] init] autorelease];
>>> 
>>> // Keep a pointer to this object around so that curl can give it back to
>>> us in callbacks
>>> curl_easy_setopt(handle, CURLOPT_PRIVATE, CFRetain(result)));
>>> 
>>> 
>>> The static analyzer tells us that result is leaked (which, without it
>>> knowing about curl, it does look like). However, it's not actually being
>>> leaked and gets cleaned up later when we clean up the CURL handle. Is
>>> there any way to silence this analyzer warning? We'd like to get our
>>> project analyzer-warning free and require no warnings before committing
>>> things.
>>> 
>>> -- Joe Ranieri
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>>> cfe-dev at cs.uiuc.edu
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>> 
>> 
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